Circular chaser die head



March 27, 1934.

Filed June 7, 1950 2 Sheets-Sheet MA W2 1 Q 1 Mg vi w mw u QHMHWVR min . R nmv a. a v0.

w. J. HOGG CIRCULAR CHASE-R DIE. HEAD.

' March 27, 1934.

Fil ed June 7, 1950 2'SheetsSheet 2 UNITED STATES PATENT OFFICE.

CIRCULAR Cnasna pm HEAD William J. Hogg, Cleveland, Ohio, assignor to The National Acme Company; Cleveland, Ohio, a

corporation of Ohio Application June 7, 1930, Serial No. 459,700

24 Claims. (Cl. 10-103) A further object of the invention is the provision of improved supporting means for the chaser effective to determine the amount to be ground off the chaser at each grinding thereof and also insure the proper re-setting of the chaser after grinding.

A further object of the invention is the provision of an improved chaser supporting block for threading dies.

A further object of the invention is the provision of an improved circular chaser for threading dies.

By the provision of a circular chaser the advantage of an extremely long life chaser, usually from twenty to thirty times the life of an ordinary chaser, is obtained. In fact with the ordinary chaser they can be ground only'about five times and about twelve hundred pieces can be made 'per grind, whereas with this improved circular chaser they can be ground or sharpened at least twenty-five times and about seven thousand pieces per grind obtained.

In this improved die chaser the grooves of the chasers are cut straight and not spiral for it has been found that spiral grooves are impractical and have never been successful for the reason that it is necessary in the re-grinding of the chasers to grind all four chasers alike which it is practically impossible for anyone to do, especially as the cutting edge of one chaser has to be set differently from the cutting edge of another chaser.

In the present improvement while the grooves are formed straight and not spiral, nevertheless the chasers are so set that they have all the'efiect of the spiral grooves without any of their disadvantages. By having the grooves circular instead of spiral each chaser can be ground independently of the others without interfering with the proper cutting when the chasers are reset in the head, whereas with the spirally formed chaser this cannot be done as they must all be ground at the same time with relation to each other. In the present improvement the chasers are somewhat tapered, the diameter at the front of each being less than that at the rear, with the result that the front portion of the chaser does the cutting while the rear half guides or pulls the chaser onto the work, the grooves acting as a guide; The cirof that cutting edge so that if the stock or-ma- 5 terial which is to be cut is larger in diameter, say of an inch larger than the cutting diameter, this front cutting edge will act as a turning tool and thus turn off or shave the work to the proper diameter before cutting the thread.

Therefore, an important object of-the invention is the provision of an improved circular chaser having circular parallel grooves instead of spiral grooves so mounted on the die body that the chasers are inclined relative to the front face of the body, together with means for so supporting the chasers that the grinding and re-setting thereof will be accurate and facilitated and which means comprises a pair of serrated bushings.

To obtain the proper efliciency with a chaser, of this kind the cutting edge of the circular chaser has to be set as near as possible to the center of the work. Therefore, an adjustment is necessary to bring this cutting edge to the center or suflicient material has to be removed-from the cutting edge to line up the chaser.

Experiments have been made with these circular chasers using a single set of serrations for each chaser, but it has been found that this requires that approximately of an inch be ground off the cutting edge of the chaser each time it is ground, whereas in the present improvement it has been found that it is only necessary to grind off considerably less material to bring, the cutting edge in line with the work, thus materially prolonging the life of the chaser. With a circular chaser having a bushing provided with a single set of serrations set of an inch apart, which was necessary because. any finer setting of the serrations would not have withstood the pressure of the chaser on the work and would will know that the cutting edge will always come in line with the work with all of the chasers properly set relatively to one another with the coarser serrations acting and taking the pressure off the cutting edge of the chasers. other words, while still retaining the coarser serrated bushing to sustain the pressure on the chaser, the chaser can have its cutting edge ground off materially less than of an inch and 'be accurately re-set in accordance with that finer grinding.

Furthermore, one of the advantages of the present improved circular chaser is that by removing the grooves therefrom and retaining the cutting edge only, the tool can be used as a hollow mill to turn the shank or shoulders on bolts, studs, etc., of brass or steel and thus be used in place of the one piece hollow mill ofiered to the trade with the advantage that the four cutting edges of the four circular cutters can be ground independently with any clearance cutting angle required for different alloy metals and with the further advantage that the cutters can be opened and closed and thus adjusted and so avoid marring the work by the tool when the tool is removed from the work which is not possible with the usual old style mill which required a subsequent finishing of the work to remove these marks.

Furthermore, in the present improvement by having the chasers set inclined, the cutting edge is brought higher than the rest of the cutter at the front or forward edge of the chaser thus always giving a clearance for the chips similar to a turning tool, while permitting the chaser to be used as a hollow mill without any changes in the die head.

In the drawings accompanying and forming a part of this specification Fig. 11s a view of the die body with the die cap and certain related parts in section.

Fig. 2 is a longitudinal sectional view of the threading die as shown in Fig. 1.

Fig. 3 is a face or front view of the die.

Fig. 4 is a front view of the die with the chasers removed and showing the serrated bushings in section, taken on the line 4-4 of Fig. 2.

Fig. 5 is a side view of the die illustrating the means for setting the chasers with relation to the work.

Fig. 6 is a perspective view of the adjustin rings.

Fig. '7 is a front view of one of the circular cutters or chasers.

Fig. 8 is a rear View thereof.

Fig. 9 is an enlarged front view of the serrated bushing.

Figs. 10, 11, 12 and 13 are partly sectional views of four circular chasers or cutters and their supporting chaser blocks, 'illustrating the angular position or setting of the chasers with relation to each other.

Fig. 14 is a cross sectional view '0 apart of a circular chaser and its block, illustrating the bushing in position and the holding screw for securing the chaser on its block.

Fig. 15 is a rear view of a form of chaser holding block, and

rangement ofparts which are illustrated in the accompanying drawings, since the invention is capable of other embodiments, and that the phraseology which I-employ is for the purpose of description and not of limitation.

As the improvement has primarily to do with the circular chasers and the manner of supporting and setting them, a brief description only is deemed necessary of the rest of the die which in the main may be similar to threading dies heretofore patented by the National Acme Company and in the present instance comprises a slotted body 2 having a shank 3 for attachment to the tool spindle holder of the machine. Upon this shank body is located a shiftable cap or housing 4 having a grooved collar 5 by means of which the cap may be shifted in the usual way by the means provided for that purpose in the machine. Located within the cap which has at its front edge four circumferential cam surfaces 6 cooperating with suitable cam surfaces on the chaser blocks is what may be termed a float or adjusting ring 7, see Fig. 6, having a fixed guide pin 8 in position to project into an opening in the rear wall of the die body. This ring is held against movement axially of the die by a shoulder screw 9 projecting through a shouldered arcuate slot 10 formed in the adjusting ring. This slot permits rotary or circumferential movement of the adjusting ring and the die body since the two are connected together by the pin 8 while permitting relative shiftable movement of the die body and cap axially of the die. This circumferential movement is obtained by a pair of adjusting screws 11 carried in suitable threaded 110 openings of the cap. These screws engage lugs 12 secured 'to the rear wall of the adjusting ring, these lugs projecting into arcuate recesses 13 located in the rear wall of the cap. By adjusting these screws, one inward and the other outward, the adjustable ring and the die body, owing to the connecting pin 8 will be rotated relatively to the cap or housing and this rotary movement of the die body causes the chasers 'to move inwardly toward the work or outwardly therefrom, according to the adjustment desired, owing to the four cam faces 6 hereinbefore referred to on the cap, which engage the surfaces of the chasers. By this means the chasers are adjusted for the proper diameter of the work to be threaded and this adjustment is controlled by the usual proper fractional graduations 14 on the adjusting ring and showing through an opening 15 in the cap.

The front face of the diebody is provided with a plurality of chaser receiving slots or recesses 130 15' shown herein as four in number for positioning and guiding the circular chasers and theirblocks. Each of these recesses is of T-shaped form for the reception of a one piece stepped correspondingly shaped chaser block 16 to which the 135 chasers are suitably secured. Each of the chaser blocks or plates 16 is provided with a rearwardly extending pin 1'7 projecting into a circularly formed slot 18 in the rear of the T-shaped slot 15 of the body and in this slot is located a spring 1 0 19 and a headed plunger 20 in position to engage this rearwardly extending pin of the chaser block thereby to shift the chaser outwardly when the cap-is withdrawn rearwardly and also to hold the chaser blocks with their cam faces in engagement 145 with the cams of the cap and by this spring means the chasers are opened or released at the proper time. Each of the T-shaped chaser blocks is provided with what is usuallydesignated as a land surface 21 curved circumferentially of the 150 die but straight in the direction of the depth of the die for cooperation with a cam formed surface 6 of the cap or housing whereby on the relative rotation of the body and cap the chasers are adjusted to make the proper cut.

In the rear of this-land surface the chaser blocks are provided withan inclined or cam surface 21' operative at the proper time to force or push the cap rearwardly thereby to permit the chasers to be opened to their full extent by the springs 19 and so release the work.

The front face of each supporting block is inclined transversely thereof, whereby the chasers 22 will be angularly set or inclined to the front face of the die body (see Figs. 1, 2 and 14) so that while the grooves 23 of the chasers are cut circularly straight and not spirally they yet have the effect of spirally cut grooves. The front faces of the die blocks thus being formed on an angle in relation to the front face of the diebody, gives the proper angular setting to the circular chasers 22 and controls the proper cutting edge and clearance thereof.

Each of the chasers or cutters 22 is substantially circular but with a segment thereof removed and has substantially circular straight parallel grooves 23 cut therein instead of spiral threads and with a segment thereof removed, the grooves terminate in a depthwi'se cutting edge 24. The circular chaser is turned and ground on a slight taper on the outside diameter to allow the proper clearance and guide for the chaser angle, the diameter at the front being less than that at the rear of the chaser, with the result that the front portion of the chaser does the cutting while the rear portion guides or pulls the chaser onto the work with the grooves acting as a guide except on chasers used for tapered thread where the full width of chaser is engaged when cutting the thread.

' By locating the chaser in an angular position on the chaser block a proper clearance and lead for the thread is obtained and by using this angular location of the chaser, the chasers can be ground independently and not in sets as heretofore required when the chasers were provided with spiral grooves. In other words, when circular chasers were provided with spiral grooves all four chasers had to be ground on the cutting edge exactly the same to secure proper cutting position and it was practically impossible for any operator to adjust them correctly. All four chasers are formed exactly the same but the height from the rear face at the point of the cutting edge will vary so that in, manufacturing these chasers all the chasers are machined exactly the same until the last operation when the back faces of the chasers are ground to suit the position of the cutting edge and consequently the position of the circular chaser endwise will always remain the same in relation to the top point of the thread. This is a very important point for without this the structure would be too complicated for the average operator to set and impractical for general use.

When milling the chaser grooves, it is necessary that the circular chaser blank be tipped at a predetermined angle equal tothe same angle that it is tipped on the chaser block-when mounted in place. This angle on the top face of the block is governed by the helix angle of the thread on the work being cut. The lower diameter at the bottom of the chaser is greater than the diameter at the top or counterbored section. This difference in diameter of the chaser is pre-determined according to the pitch of the thread to be cut and the diameter of the work being threaded in order to keep the diameter of the circular chaser as large as possible.

Therefore, to obtain the proper position of the chasers, each chaser is ground during. the last operation on its back face to suit the particular position of the cutting edge in the die body, a little more being ground off the back of one chaser than off the back of another (see Figs. 10 to 13). This grinding however, is in a perfectly straight direction or plane and .does not give the angularity of the chaser relatively to the body as this is obtained by the angularity of the front face of the chaser blocks, but it does give the difierent positions of the chasers, as shown in said Figs. 10 to 13, wherein it will be noted that in Fig. 10 the distance between the lines 12 is less than it is between the lines 3-4 in Fig. 13, the letters A and B showing how the grinding gradually varies in the four chasers of the set.

In the front face of each chaser block is located a circular serrated opening 25 for the reception of a serrated bushing 26 having serrations thereon for instance 1/64 of an inch apart. This serrated bushing has an integral bushing 2'7 of larger diameter in front thereof having serrations thereon for instance1/32 of an inch apart and the chaser has its back face provided with a serrated circular opening 28 corresponding to the serrations of the larger bushing and these several parts, the chaser, the detachable and rotatable two section bushing and chaser block are secured together by a screw or bolt 29 having a counterbored front end 30 for the reception of a suitable tool to release the chaser from its block, this screw being left handed whereby the cutting of the chaser will tighten the screw. By means of this or a similar combination of serrations not only is the setting and grinding of the chaser facilitated but the turning of the chaser on its block is prevented. The front face of the bushing is suitably graduated as at 27 to facilitate the setting of the parts. .It will be understood of course that as each chaser is successively ground it is moved around the serrations to bring the cutting edge thereof to the proper point. Thus the serrated bushing acts as a pilot on which the circular chaser is mounted on the one piece chaser block and insures that the cutting edge of the chaser be set in the proper position for cutting.

The counterbored front end 31 of the chaser not only provides a chip clearance when the chaser is cutting but permits the proper grinding of the chaser so that'it will cut properly. The cut-away or removed segmental portion along the length of the chaser forms a cutting edge which the counter-bored front end intersects while the serrated opening in the back of the chaser is of less diameter than the counter-bored opening and does not intersect the cutting edge.

From the foregoing it will be seen that if a bushing were used having only one set of serrations, say for instance 1/ 32 of an inch apart, which would be necessary in order that they be not too fine to support the chaser, then the chaser would have to have its cutting edge ground off 1/32 of an inch each time it was ground, but by having a bushing of two diameters with different circumferentially spaced or graduated serrations the result is that, if for instance, the number of serrations on the smaller bushing is less or approximately one-half of the number of serrations on the larger bushing, the chaser can be ground of! 1/64 of an inch each inch.

Insetting the chaser to a new position, the bushing is moved clockwise one serration in the chaser block. The chaser is then set back anticlockwise one serration. Now, if the smaller bushing has thirty serrations and the larger one has forty serrations this eliminates a full serration movement, in other words, there is a ratio of practically four to one. To illustrate this, consider a pipe chaser for a tap die. 1" equals the diameter of the chaser which is 3.1416 in circumference. 3.1416 divided by thirty equals .1047 which is the movement when only moving the bushing clockwise in the chaser block and 3.1416 divided by forty equals .0785 which is the back movement when moving the chaser anticlockwise on the bushing. Thus we have moved the thirty serration circumference ahead one complete serration, but have moved the chaser on the bushing back in proportion or in ratio of thirty to forty, therefore subtracting .0785 from .1047, the remainder is .0262 which is the amount left to grind off the face for the new setting, thus the amount to be ground off of the circular chaser is in proportion as thirty is to forty.

From the foregoing it will thus be seen that I have provided an improved die having circular chasers of improved form and construction together with improved means for supporting them and which supporting means includes means for pre-determining the exact amount to be ground off of the chaser at each grinding thereof, while insuring not only long life to the chaser but an accurate re-setting of the chaser to correspond with such grinding.

Among the numerous advantages of this improved circular chaser is not only the longer life thereof as compared with the ordinary form of chaser because there is quite a few inches of periphery provided for grinding, but the chaser grooves can be readily circularly ground, the cutting edge is protected when the die is opened as the cutting edge is rolled away from the chip instead of dragging through, the heat is carried away from the cutting edge rapidly due to the large cross section of the chaser. The chaser can be readily made in a screw machine and has a clearance similar to a milled chaser, the cutting edge can be readily sharpened, it can be readily taken out and returned, and there is reduction in the stock or number of chasers required to be carried on hand.

The chasers can be used for right and left hand threaders by simply changing the angle of the chaser block slide opposite to that for right hand thread cutting.

It will be understood of course that the coarseness of the grooves of the circular chaser can be varied as may be desired.

It is to be understood that by describing in detail herein any particular form, structure or arrangement, it is not intended to limit the invention beyond the terms of the several claims or the requirements of the prior art.

Having thus explained the nature of my said time instead of 1/32 of an invention and described a. way of constructing and using the same, although without attempting to set forth all of the forms in which it may be made. or all of the modes of its use, I claim:

1. A tool of the class described having a body, a circular chaser and chaser supporting means including means having a plurality of differently spaced but similarly formed means insertable in both the chaser and supporting means, and cooperating with similarly formed means of the chaser and supporting means for pre-determining the amount to be ground off the chaser at each grinding thereof.

2. A tool of the class described having a body, a circular chaser, chaser supporting means including means for pre-determining the amount to be ground off the chaser at each grinding thereof and comprising a serrated bushing having a. plurality of sets of differently spaced serrations insertable in both the chaser and supporting means, and co-operating with similarly formed means of the chaser and supporting means.

3. A tool of the class described having a body, a set of chaser carrying blocks radially shiftable in the body, and a set of circular chasers carried by said blocks, each having its back face ground off in a straight direction or plane, one to a greater extent than its-preceding chaser, thereby togive different cutting positions to the chasers, each of said blocks having an inclined front face for setting the circular chasers inclined to the front of the body.

4. A tool of the class described having a body, a set of chaser carrying blocks shiftably supported by the body and having land and cam faces, circular chasers carried by the blocks and located at an angle thereto, each of said chasers having 05 circular straight grooves therein'around its circular periphery and also having its back face ground off in a straight direction or plane, one to a greater extent than its preceding chaser.

5. A tool of the class described having a body, a set of shiftably supported chaser blocks carried thereby and each having a land and cam face and an inclined front face, a set of circular chasers carried by said blocks and each having circular straight grooves therein around its circular periphery, each of said chasers having its back face ground off in a straight direction or plane, one to a greater extent than its preceding chaser, thereby to give different cutting positions to said chasers, each of said chasers being angularly supported relatively to-its supporting block.

6. A tool of the class described having a body, a set of shiftably supported chaser blocks carried thereby and each having a land and cam face and an inclined front face, a set of circular chasers carried by said blocks and each having circular straight grooves therein around its circular periphery, each of said chasers having its back face ground off in a straight direction or plane, one to a greater extent than its preceding chaser, thereby to give different cutting positions to said chasers, each of said chasers being angularly supported relatively to its supporting block, and means for positioning the chaser on its block and effective to pre-determine the amount to be 135 ground off the chaser at each grinding thereof.

7. A tool of the class described having a body, a set of shiftably supported chaser blocks carried thereby and each having a land and cam face and an inclined front face, a set of circular 140 chasers carried by said blocks and each having circular straight grooves therein around its circular periphery, each of said chasers having its back face ground off in a straight direction or plane, one to a greater extent than its preceding 145 chaser, thereby to give different cutting positions to said chasers, each of said chasers being angularly supported relatively to its supporting block, means for positioning the chaser on its block and effective to pre-determine the amount to be 5 ground off the chaser at each grinding thereof and comprising a serrated bushing having a plu rality of sets of differently spaced serrations, fitting into and co-operating with similarly formed serrations of the chaser and block. H

8. A tool of the class described having a body, a set of shiftably supported chaser blocks carried thereby and each having a land and cam face and an inclined front face, a set of circular chasers carried by said blocks and each having circular straight grooves therein around its circular pe-' riphery, each of said chasers having its back face ground off in a straight direction or plane, one to a greater extent than its preceding chaser, thereby to give different cutting positions to said chasers, each of said chasers being angularly supported relatively to its supportingblock, means for positioning the chaser on its block and effective to pre-determine the amount to be ground off the chaser at each grinding thereof, and comprising a detachable and rotatable serrated bushing having a plurality of sets of differently spaced serrations, fitting into and c -Operating with similarly formed serrations of the chaser and block.

9. A tool of the class described having a body, a set of chaser blocks carried thereby having angular front faces and a set of circular chasers having circular straight grooves around its circular periphery and angularly set on said blocks, each of said chasers having its back face ground off in a straight direction or plane, one to a greater extent than the preceding chaser, and means for securing the chasers to the blocks.

10. A chaser block, a circular chaser each having serrated openings, and a bushing fitting into having serrations around its periphery for positioning the chaser on the block.

'11. A chaser block and a circular chaser having serrated circular openings of different diameters and a detachable and rotatable serrated bushing fitting saidopenings.

12. A chaser block having its front face provided with a serrated opening, a circular chaser having its rear face provided with a serrated opening, and a detachable and rotatable serrated bushing of different diameters having two sets of differently shaped serrations adapted to project into the serrated front of the block and serrated rear of the chaser, said bushing having graduation marks on its face.

13. A tool of the class described having a body, a circular chaser, chaser supporting means including means for predetermining the amount to beground off the chaser for each grinding thereof and comprising a stepped bushing having serrations around the periphery thereof and insert-- able into and co-operating with similar serrations in the block and chaser, the serrations on one step being different from those on the other step of the bushing.

14. A chaser block having a serrated opening at its front face, a circular chaser also having a serrated opening at its rear face, a bushing projecting into both of said openings and having serrations around its periphery meshing with the serrations of both of said openings, one set of said serrations being spaced differently from the other.

15. A chaser block having a serrated opening at its front face, a circular chaser also having a serrated opening at its rear face, a bushing projecting into both of said openings and having serrations around its periphery meshing with the serrations of both of said openings, the diameter of one of said openings being-greater than that of the other, said bushing also having diameters corresponding therewith.

16. A detachable stepped bushing having two differently formed sets of serrations for positioning a circular chaser on a chaser block and adapted to fit into similarly formed openings of a chaser and block.

1'7. A detachable bushing for positioning a circular chaser on a chaser block and having serrated exterior surfaces of different diameters, one in rear of the other, the diameter of each serrated surface being the same from end to end thereof and adapted to fit into similarly formed openings of a chaser and block.

18. A tool of the class described having a body, a circular chaser, chaser supporting means including means for predetermining the amount to be ground off the chaser at each grinding thereof and comprising a bushing having exteriorly located serrations, the front partthereof insertable into and co-operating with similarly formed interiorly located serrations of the chaser and the rear part thereof insertable into and co-operating with similarly formed interiorly formed serrations of the chaser supporting means.

19. A tool of the class described having a body, a circular chaser, chaser supporting means including means for predetermining the amount to be ground off the chaser for each grinding thereof and comprising a stepped bushing having exteriorly located serrations, those of one step insertable into and co-operating with similarly formed interiorly located serrations of the chaser and those of the other step insertable into and co-operating with similarly formed interiorly located serrations of the chaser supporting means.

20. A serrated bushing having different diameters and provided with serrations of different degrees of fineness and constructed to fit into similarly formed openings of a chaser and chaser block for facilitating the grinding and setting of the chaser, said bushing having a graduated face.

21. A serrated bushing having different diameters and provided with serrations of different degrees of fineness and constructed to fit into similarly formed openings of a chaser and chaser block for facilitating the grinding and setting of the chaser, said bushing having a graduated face corresponding to the serrations on the smaller diameter of the bushing.

22. A tool of the class described having a body, a set of sliding chaser blocks having plane front faces, a set of collapsible circular chasers carried thereby having their back faces engaging the plane front faces of the blocks and located at an angle to the blocks, each having a face ground.

off in a straight direction or plane differently from a companion chaser to give different cutting positions to the chasers.

23. A radially shiftable chaser block having means at each side thereof for guiding the block for sliding movement in a die body and having in front of said guiding means a plane faced chaser supporting portion having at one end there-' its counter-bored front end and not intersecting the cutting edge for the reception of a detachable serrated bushing adapted to project into a similarly formed opening of the block, the serrations of the chaser having a different diameter from that of the block.

J. HOGG. 

